Forage choppers typically employ chopping cylinders that include a plurality of circumferentially spaced apart knives mounted on a radially extending support arms. The knives are rotated by the cylinder at high speeds and cooperate with a stationary shear bar to chop incoming crop stalks and the like into small segments. The orientation of the knives relative to the shear bar is critical to achieve proper severence and uniform length of the chopped segments. Thus, it is essential that the position of the knives on the cylinder support arms be adjustable such that proper orientation of the knives relative to the shear bar can be made upon initial installation of the knives, and as may be necessary or desirable to accommodate for wear on the part of the knives and the shear bar.
A mechanism for adjusting the position of a harvester knife along a path of travel relative to a cylinder supporting arm is disclosed in U.S. Pat. No. 3,797,766. The adjustment mechanism of U.S. Pat. No. 3,797,766, however, does not provide for a positive, two-way adjustment of the knife. An adjuster capable of positive two-way adjustment of the knife would greatly enhance and speed-up the operation of properly orienting the knife relative to the shear bar.